Spring BeanDefinitionBuilder tutorial

last modified October 18, 2023

Spring BeanDefinitionBuilder tutorial shows how to programatically create new Spring beans using BeanDefinitionBuilder.

Spring is a popular Java application framework for creating enterprise applications.

BeanDefinitionBuilder

BeanDefinitionBuilder is used to create new Spring beans programatically. It utilizes the builder pattern.

Spring BeanDefinitionBuilder example

The application creates create a simple string bean.

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 <modelVersion>4.0.0</modelVersion>
 <groupId>com.zetcode</groupId>
 <artifactId>beanbuilderex</artifactId>
 <version>1.0-SNAPSHOT</version>
 <properties>
 <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 <maven.compiler.source>17</maven.compiler.source>
 <maven.compiler.target>17</maven.compiler.target>
 <spring-version>5.3.23</spring-version>
 </properties>
 <dependencies>
 <dependency>
 <groupId>ch.qos.logback</groupId>
 <artifactId>logback-classic</artifactId>
 <version>1.4.0</version>
 </dependency>
 <dependency>
 <groupId>org.springframework</groupId>
 <artifactId>spring-context</artifactId>
 <version>${spring-version}</version>
 </dependency>
 <dependency>
 <groupId>org.springframework</groupId>
 <artifactId>spring-core</artifactId>
 <version>${spring-version}</version>
 </dependency>
 
 </dependencies>
 <build>
 <plugins>
 <plugin>
 <groupId>org.codehaus.mojo</groupId>
 <artifactId>exec-maven-plugin</artifactId>
 <version>3.1.0</version>
 <configuration>
 <mainClass>com.zetcode.Application</mainClass>
 </configuration>
 </plugin>
 </plugins>
 </build>
</project>

In the pom.xml file, we have basic Spring dependencies spring-core and spring-context and logging logback-classic dependency.

The exec-maven-plugin is used for executing Spring application from the Maven on the command line.

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
 <logger name="org.springframework" level="ERROR"/>
 <logger name="com.zetcode" level="INFO"/>
 <appender name="consoleAppender" class="ch.qos.logback.core.ConsoleAppender">
 <encoder>
 <Pattern>%d{HH:mm:ss.SSS} [%thread] %blue(%-5level) %magenta(%logger{36}) - %msg %n
 </Pattern>
 </encoder>
 </appender>
 <root>
 <level value="INFO" />
 <appender-ref ref="consoleAppender" />
 </root>
</configuration>

The logback.xml is a configuration file for the Logback logging library.

package com.zetcode;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.ComponentScan;
@ComponentScan(basePackages = "com.zetcode")
public class Application {
 private static final Logger logger = LoggerFactory.getLogger(Application.class);
 public static void main(String[] args) {
 var ctx = new AnnotationConfigApplicationContext(Application.class);
 var beanFactory = (BeanDefinitionRegistry) ctx.getBeanFactory();
 beanFactory.registerBeanDefinition("myBean",
 BeanDefinitionBuilder.genericBeanDefinition(String.class)
 .addConstructorArgValue("This is my bean")
 .setScope("prototype")
 .getBeanDefinition()
 );
 logger.info("{}", ctx.getBean("myBean"));
 ctx.close();
 }
}

The example creates a simple bean of type String using BeanDefinitionBuilder.

var beanFactory = (BeanDefinitionRegistry) ctx.getBeanFactory();

A bean factory is retrieved from the application context with getBeanFactory.

beanFactory.registerBeanDefinition("myBean",
 BeanDefinitionBuilder.genericBeanDefinition(String.class)
 .addConstructorArgValue("This is my bean")
 .setScope("prototype")
 .getBeanDefinition()
);

We register a new bean with registerBeanDefinition.

logger.info("{}", ctx.getBean("myBean"));

We get the bean from the application context with getBean and log it.

$ mvn -q exec:java
20:51:05.970 [com.zetcode.Application.main()] INFO com.zetcode.Application - This is my bean 

We run the application.

In this article we have used the BeanDefinitionBuilder to register a new Spring bean programatically.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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